This invention relates to curable oxirane formulations and methods for curing oxiranes to produce water-insoluble materials.
Most coating and other product formulations are employed in a fluidized state and are then dried or cured to solid continuous films or articles that are water-resistant. The films are also adherent to the substrate to which they are applied. Thus such fluid formulations usually contain a vehicle and miscellaneous ingredients such as pigments, extenders, fungicides and the like. The vehicle is a fluid consisting of a solution or a mixture of a binder with a thinner or solvent. The binder is the primary constituent since it binds itself and any optional ingredients to the substrate or surface of the object being coated. See, for example, Bobalek and Fisher, Organic Protective Coatings, Reinhold, (1953); and Martens, Emulsion and Water-Soluble Paints and Coatings, Reinhold (1964).
Of particular interest as coatings or binders are oxirane compounds such as epoxy resins and various polymers containing oxirane groups. To enable the coatings to dry or cure to form continuous adhesive films, the oxiranes that are cured after application to the substrate have generally been employed. In order that the coatings have a desired water resistance, the oxiranes used are generally hydrophobic and are therefore, not soluble in water. Thus, the liquid thinner or solvent, usually required to fluidize the oxiranes, has generally been an organic solvent such as xylene, toluene, various alcohols and the like. Such solvents are generally more expensive than water and are often toxic or flammable, thus requiring expensive precautions when coating formulations containing them are stored and used.
In view of the foregoing disadvantages of such organic solvents or thinners, it is highly desirable to employ an oxirane which can be dissolved by or dispersed in water and yet will produce a water-resistant film when applied to a substrate and then dried or cured. While such water-based fomulations have been made and cured in the past, it is desirable to provide curable oxirane formulations which cure to form coatings exhibiting further improvements in properties such as adhesion and water-resistance. It is also desirable that such formulations do not yield odorous by-products upon curing.